Concepts musica artificiosa and rationality are part of modern aesthetic-philosophical discours of music. Arnold Schönberg and Anton Webern can be considered an originators of the discours of rationalism. Schönberg as a theoretician and composer revived the ancient topic of music history and brought it to the fore. Music of the 20th century discovered its potential of rationality, which was possible due to new relationships between the theory of music and composition, strong involvement of composers in a theoretical reflection of their music. A personal union of a theoretician, philosopher, aesthetician and composer led even to blurring of a traditional border line between theoretical reflection and composition. Composers of the darmstadt serial avant-garde epitomize this cultural phenomenon of rationalism, but the originator was A. Schönberg. Th. W. Adorno was first schönbergian aesthetician-theoretician who explored phenomenon of Schönberg's rationality in its ambivalency and possible negative implications. His analyses in confrontation with Schönberg's reflection are the point of departure of this study.